Paper No. 14
Presentation Time: 8:00 AM-6:00 PM
SOIL BIOTA COMMUNITY'S RESPONSE TO C3-C4 TRANSITION IN THE BRADY SOIL, CENTRAL GREAT PLAINS, PLEISTOCENE-HOLOCENE TRANSITION
We are investigating how the soil biota community responded to the C3-C4 transition seen at the Pleistocene-Holocene transition, which also records a change from a cool, wet climate to a warmer, drier climate. Evidence for this transition is preserved in the Brady Soil in western Nebraska as an increase in C4 grasses and a decrease in C3 grasses. By measuring trace fossils and using burrows as a proxy for body size and biodiversity, we are looking for changes in individual taxon size and in the community diversity with respect to shifts in climate and vegetation. The Brady Soil is the best place to study the effects of climate change on soil biotic communities across the Pleistocene-Holocene transition (PHT), as it is well studied and contains independent lines of evidence for changes in vegetation and climate. Fieldwork is being conducted north of Wauneta, Nebraska, at the Old Wauneta Road Cut. A master section was measured through the Peoria Loess, Brady Soil, and Bignell Loess to capture sediments that record conditions before, during, and after the PHT. Samples for analysis for grain size and color were collected. Burrows are described according to their architectural and surficial burrow morphologies and burrow fill. The trace fossils represent burrows made by prairie dogs, beetle larvae, and cicada nymphs. Prairie dog burrows are present below, within, and above the Brady Soil. Cicada nymph and beetle larvae burrows are most abundant within the Brady B horizon. The information collected will be used to determine the ichnotaxonomic diversity that represents the soil community. As many examples as possible of length and diameter was measured for each kind of burrow. This data will be used to examine the response of individual soil ichnotaxa to the changes in stable carbon isotopes that records the C3-C4 transition. An ichnotaxonomic study will be conducted and statistical analysis of burrow diameters performed.